What the Fire Stole, It Returns
by ZeFandomKat
Summary: The lives of many different people are suddenly thrown into chaos when an evil organization begins to gain power. Big Hero 6 feels an increasing need to spread out their operation. The Avengers feel ready for anything Hydra can throw at them. They aren't prepared, however, for Hydra's newest plaything. A young man who was considered dead to the rest of the world.
1. Prologue

**What the Fire Stole it Returns**

 **Prologue**

The soft sounds of someone tinkering with metal filled the room, light produced by both stars and streetlamps shining in through the partly opened window as a wind gently breezed through. There was a young boy sitting on a bed near the middle of the room, frowning as he wrestled with a mound of wires and metal panels. The tip of his tongue poked out from between his teeth as his eyebrows furrowed in concentration, before he let out a crow of accomplishment. He inserted a green wire into what could now be recognized as a helmet, and smirked victoriously when it booted into life. Jumping off of the bed with the item tucked safely in his arms, he made his way over to a computer sitting on a cluttered table.

"Ow," He said casually, sitting down in the chair and hooking the helmet up to the computer. A sound not unlike a vacuum cleaner started, but the boy didn't seem concerned with it. Instead he was typing away as a large, marshmallow shaped robot inflated near the stairway. It stepped out of the box and turned towards the boy.

"Hello, I am Baymax, your personal healthcare companion. What is it that you need Hiro?" It- Baymax- asked, walking slowly over to the desk.

"I fixed it Baymax, your scanner should have an increased range of 3,000 percent now," Hiro replied, unplugging the helmet from the computer and standing up. He turned towards Baymax and placed the helmet on top of his head. "Run a system diagnostic test."

"Running diagnostic check now," Baymax said, and stilled for a few moments. "Check complete. My scanner's range has increased to the designated parameters; everything is in working order."

Nodding in satisfaction, Hiro smiled up at Baymax and held out his fist. Baymax looked at it for a moment before he met Hiro's fist with his own. "Ba-la-la-la-la-la-la," they said in sync, and Hiro's smile widened. He stretched his arms out above his head leisurely, yawning as he did so.

"Hiro, it is 2:30 AM. A good night's rest is needed in order to maintain a healthy body and mind. Might I suggest that you go to bed now?" Baymax said, turning around to follow Hiro as he made his way around the room, picking the various leftover wires, metal, and tools off of his bed and placing them in their proper places.

Hiro rolled his eyes but smiled nonetheless. "Yeah yeah, give me a minute Baymax. I don't want a screwdriver poking into my back while I sleep," he replied good-naturedly, checking to make sure that everything was off of his bed. Satisfied that it was clear, he clambered into it and burrowed down beneath the covers. Yawning once more, Hiro felt his eyes drifting closed as he was lulled into sleep.

Baymax tilted his head. "Music is often found to relax people when they are experiencing insomnia. Would you like me to play some Mozart?" Soft classical music suddenly filled the small place, and Hiro laughed quietly.

"No thanks Baymax, I'm good. I'm just glad I finally upgraded your scanner, it's been bugging me for days. This'll make catching people a lot easier," Hiro mumbled, already slipping back into the realm of dreams. The music stopped, and Baymax monitored Hiro for a moment longer until he was sure that his patient was truly asleep. Then he turned around and waddled back to his charging station, deactivating to wait until the next time he was needed.

._._._._._._._._._._._._._._._.

A pounding on the door of his cell awoke the single occupant, although he didn't jump or startle like he had when he had been new there. Instead he simply sat up, slid his feet into his shoes, and walked over to the door with his hands held out in front of him. A guard opened the door, armed with a small armament of weapons and a dispassionate expression. The prisoner made no move to speak, and neither did the guard. Instead he simply led the prisoner down the bland hallway, after making sure that he was handcuffed. After a few twists and turns, passing by several doors from behind which disturbing sounds were emanating from and several where the quiet was unsettling, the guard stopped in front of another door. This one was guarded by two men on either side, each dressed in the exact same way and with the same bored expression as their co-worker. They didn't even look at the prisoner, although he was used to this by now as well. He didn't try to ask them questions or make a witty remark as his guard entered in the code for the room and entered. Instead he followed him in silently, the door closing once more with a quiet gust of air. The guard motioned the prisoner to step forward and hold out his hands, and the prisoner did so with no complaint or whine, expression neutral. Unlocking the handcuffs and reattaching them to his tool belt, the guard stepped back and stood by the door, settled in for the rest of the day. The prisoner turned towards the rest of the room, and while its high tech equipment and tools would have made him exceedingly excited on a normal day, he maintained his facade that was as blank as the guards'. He made his way over to the largest table in the middle of the room and picked up a sheaf of papers lying on its surface. They were his instructions for the day; skimming through them, the prisoner almost huffed. It was the same as usual, they wanted improvements on his latest bot. Placing the papers back down, the prisoner rolled up his sleeves to set to work, revealing a tattoo on his inner arm that had a barcode and a simple message.

Asset #2.

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Hey everyone! This is my newest story. It takes place in the Marvel Universe, mainly focusing on Big Hero 6. The other Marvel characters and plot that you know (Iron Man, Captain America, Black Widow, etc.) will stick mainly to the Movie Universe. Big Hero 6 will stick to the movie a lot as well. However, I will change several things. This story just has more in common with the Movieverse than the Comicverse, it does not mean that they are exactly the same. Also, fair warning now, this will most likely have the Hidashi ship. In fact I'm counting on it. So if you do not like that ship, this is not the story for you. Now as for other ships, I don't know. I don't really like any other Big Hero 6 ships, and for Marvel they would be few and far between. If you have any suggestions feel free to leave them, I can't promise that I'll listen to you but it couldn't hurt.

Also, another warning: I take forever to update. Just look at my profile, my other fics haven't been updated in forever (and I'm still not entirely sure I will update them). That being said, I definitely have a lot of steam for this story. I'll try to update every week, and I'll let you know if I am unable to meet that standard. As for the rating, it should go to about a high T, but only because of some violence. It's around the level of the Hunger Games, if that makes any sense to you.


	2. Chapter One

**Chapter One**

Bright morning sunlight filtered in through the window, shining directly on Hiro's face. He groaned, trying to bury his head under his pillow to no avail. After a few minutes of useless adjusting, Hiro threw the covers off of his body with a grumble. Getting to his feet, he shuffled his way over to the bathroom to take a shower in an attempt to wake himself up. Fifteen minutes later, Hiro padded out back into his room, hair damp but his eyes considerably brighter than they had been before. Stretching his arms out above his head, Hiro looked at the clock on his phone to see what time it was and his eyes widened when he saw the time. 11:07 AM. Class started at 11:30 and it took twenty minutes to get to the school. Normally he wouldn't be concerned about missing class, since he usually already knew everything his teachers talked about, but that day they were going to have a test. Hiro knew he'd be able to do it with ease, as long as he was actually there to take it.

Hiro darted around the room, gathering his stuff together as quickly as possible. He was running around so much that he kicked his foot against the bed frame, and the seventeen year old had to hold himself back from letting out a slew of curses because he definitely did not need Baymax activating at that moment. Once his papers and books were shoved haphazardly in his bag, he grabbed Baymax's case and dragged it down the stairs with him.

His Aunt Cass was already down at the cafe, and Hiro waved goodbye to her as he ran out the front doors. She didn't bother to call after him; checking the time herself, she rolled her eyes at her nephew's behaviour and then continued on tending to customers. Hiro being late for something was not a new occurrence around their house.

Hiro ran full blast down the streets towards his bus stop, seeing the bus about to pull away. He waved his right arm around frantically (the one that wasn't pulling Baymax along) and sighed with relief when the driver stopped. As he clambered up the steps, he offered a sheepish smile to the man, who huffed and gestured towards the seats. Hiro plopped down in one near the front as the bus pulled away from the curb, panting as he caught his breathe. Well, at least he could say that he'd gone for a morning jog.

Anxiously waiting for the school to appear, Hiro made sure that Baymax hadn't been damaged in his mad sprint to catch the bus. Luckily, the case didn't appear to be damaged, although he would probably have to replace the wheels soon. The bus slowed to a halt, and Hiro looked up to see the SFIT building gleaming in the sunlight. He hurriedly got up and thanked the driver, then ran down the steps and into the building. He only had five more minutes to get to class before he was late, and the teacher would lock the door. Hiro groaned as he wondered why it had to be Professor Hartman's class taking a test that day. The man seemed to have it out for Hiro, always thinking that Hiro was looking down on him when actually Hiro had a deal of respect for the man. His behaviour, however, did not make Hiro like him, and each time his grade was brought down a few points out of spite he found his respect dwindling. Professor Hartman would certainly take pleasure out of having Hiro fail a test, of that he was certain. Finally, Hiro slid in front of the door, only one minute until the beginning of class. He dashed hurriedly inside and almost leaped for his chair, only relaxing once he was firmly in place. The other students didn't pay him much heed; Hiro heard one guy telling his friend that Hiro had some mad skills while a girl clapped softly a few seats to his left. Hiro grinned to himself, watching Professor Hartman close the door with a sour look on his face. College was a lot better than high school and middle school combined; most students didn't have the same prejudices or follow the same stereotypes that younger people did. Hiro bet that he could show up to class in nothing but his underwear and no one would have even bat an eye; in fact, they would probably think that he had the right idea. Professor Hartman handed out everyone's test, and Hiro filed away his other thoughts and focused on his paper. He could probably finish it and leave in ten minutes, fifteen if he really took his time. That was okay with him, he had other stuff to do that day anyway besides schoolwork.

Just as he had predicted, fifteen minutes later saw Hiro handing his test in to Professor Hartman, who turned a lovely shade of purple at the completed (and more than likely 100% correct) fifty question test. If he had really wanted to keep them in the room for longer, he should have given them a bubble sheet to fill in their answers. Hiro smirked to himself as he left the room, this time walking down the hallway at a much more sedate pace. It made having to put up with all of Hartman's BS totally worth it. But, Hiro wouldn't have to put up with the man for much longer. He was going to graduate soon, and then he would be off to do other things. Hiro already was doing other things, he reflected silently as he entered the wing of the school reserved for labs. Hiro walked past several other students who were messing around and stepped over a guy laying prone on the floor with a pillow and blanket, snoring up a storm. Hiro could see Fred, Wasabi, Honey Lemon, and GoGo over in GoGo's lab, and he headed his way over there to talk with them. All of them had graduated two years previously and had been granted their own private labs by the school, since they were recognized as very promising individuals in each of their fields. The situation panned out for them all rather nicely; this way, they were able to spend more time together to plan, upgrade their gear, or just hang out than they would have regularly.

GoGo was the first person to spot Hiro on his way over, and she nodded at him in greeting. Honey Lemon looked over and smiled excitedly when Hiro finally joined them; she reached over and gave him a hug so tight he could barely breathe.

"Hiro! How are you today, how was your test?" She asked exuberantly, still holding him close to her.

Hiro managed a breathless chuckle and replied, "I aced it. And Honey, could you let me go please? I can't...breathe…"

Honey immediately released her death hold on Hiro, giggling a little. "Oops, sorry Hiro."

"It's no problem," He wheezed back, collecting his breath once again. It seemed to Hiro that he had been doing a lot of that lately.

"Hey little man, what have you been up to since we last saw you?" Wasabi asked, looking over a few reports.

"Ah, not much. I upgraded Baymax's scanner," Hiro supplied. He walked over to Wasabi and tried to look at his papers. "What's that for?"

"Oh, these?" Wasabi asked. "I'm just recalibrating my plasma lasers to achieve an even finer precision. These are just the results from the last test I ran. There would be more of them if someone," Wasabi paused to glare at Fred, who was reclining in a chair with his hands behind his head and his hat pulled over his eyes. "Hadn't decided that the plasma made the perfect backdrop to a robot invasion and messed up all of my adjustments!"

Fred peeked out from underneath his hat and grinned. "Hey, it did! I didn't mean to bump into the controls, man, the coffee maker was just looking suspicious!"

Wasabi face palmed and took a deep breathe in, trying to rein in his temper. Hiro stood off to the side with GoGo and Honey Lemon, trying to keep his laughter in. "A coffee maker is incapable of looking suspicious Fred! It's incapable of looking like anything but a coffee maker! You need to be careful around the lab, any one of these experiments could be dangerous and you could get hurt!"

Fred waved away Wasabi's words and, with a carefree grin, walked up to the man and slapped a hand on his shoulder. "That's what makes this place fun man! Don't you love the adrenaline rush of being surrounded by things that could both help and destroy you at the same time?"

Wasabi stared at Fred like he was crazy, his mouth hanging open. "No! No I don't!"

"What I'm hearing is that Fred is getting off by hanging out with us," GoGo said, popping her gum with a smirk.

Hiro and Fred let out a snort of laughter while Wasabi let out a little shriek. "GoGo! Don't say things like that in front of Hiro!"

"Why not?" She retorted, heading over to her Baymax's case and pressing the button that would activate him. "Hiro's seventeen, he can handle it. You need to woman up Wasabi."

Wasabi was left spluttering and Honey Lemon tried to cheer him up while Baymax inflated. He stepped out of his charging station, held up his hand, and said with a wave, "Hello, I am Baymax, your personal healthcare companion. How are you today?"

"We're good big guy, how are you?" Fred asked happily, leaning against the robot. GoGo sat down backwards in the chair Fred had vacated, and Hiro leaned back against a desk that had various sketches of bikes and roller blades on it.

Baymax tilted his head in confusion. "My internal systems are all running at 100%. Am I correct in that this makes me 'good'?"

"I think it does!" Honey Lemon chimed in, smiling happily at Baymax. GoGo blew another bubble and popped it before turning her attention to Hiro.

"So you finally finished Baymax's scanner?"

Hiro snapped his attention away from the others; Wasabi and Fred had started arguing again, with Honey Lemon and Baymax awkwardly trying to calm the two down. Hiro and GoGo knew that they'd be best friends again in an hour at most, all of this in the past and forgotten. Hiro nodded his head at GoGo's question. "Yeah, at 2:30 last night. That's why I slept in until 11 and nearly missed my test."

GoGo snorted and punched Hiro's shoulder. "That's why you set an alarm, knucklehead."

Hiro rubbed his shoulder and winced. He felt a pang of sadness flit through him when GoGo called him a knucklehead, but he pushed it away. He was used to pushing any of his feelings concerning Tadashi away after all of these years, it was second nature to him now. Sometimes, when he was alone, he would reflect over all of his memories with his brother. Every single memory that he could recall, even the ones that had seem stressed and horrible at the time. Now they all just made him feel sad, and each one left a bittersweet taste in his mouth. He was glad that he had gotten to spend even the limited amount of time that he had with Tadashi. Hiro knew he was better for having his brother be there for him, teaching him things about life and the world that Hiro hadn't gotten from anywhere or anyone else, not even Aunt Cass. But that just made his death all the more tragic; Tadashi was so young, only nineteen years old when he died. He had wanted to do so much, wanted to help so many people. Hiro knew that Tadashi would have given everything that he was made of to the world, and would have expected nothing in return. It hurt, it physically hurt Hiro to think about all of the things his brother could have done. But there was no point in dwelling over it and letting the grief consume him; Hiro had learned his lesson when he and the rest of the nerd herd had battled Callaghan. Hiro wasn't exactly sure what all Tadashi would have gone on to do with his life (besides helping people constantly), but he did know that he wouldn't have wanted Hiro to waste his life away mourning for his dead brother. So, while it took a lot of effort, Hiro had eventually gotten to the stage when he thought of Tadashi's death unconsciously rarely, and even when he did the sting of pain wasn't as prominent. The others, Hiro knew, went through something similar; there was an unspoken rule to not mention Tadashi, and even if they did, there was another rule in place that they could only talk about the positive things, like how Tadashi would have absolutely hated that new dance craze, and how he would have obsessively hoarded all of Fall Out Boy's new songs.

A crashing sound from the other side of the room startled Hiro and GoGo out of their respective thoughts, and they turned to see Fred underneath an upturned chair and Wasabi sprawled out on the floor a few feet away. Honey Lemon and Baymax were trying to help the two up and check for any damage, although Honey Lemon couldn't stop herself from letting out a laugh every now and then.

GoGo marched over and heaved the chair off of Fred. Lending him a hand up, she raised her eyebrow at the two men. "So, mind telling us what happened?"

Fred smiled sheepishly. "Um, it's kinda my fault. Wasabi warned me not to lean back in the chair, but then all of a sudden the world was tilting around me. He tried to grab me but the wheels kinda smacked into him and threw him across the room."

Wasabi was currently being scanned by Baymax, who reported that he was fine except for a few bruises. GoGo's eyebrow rose even further into her hairline, and she crossed her arms in front of her chest. "So you're telling me that the two of you can take on super-powered villains and huge mobsters, yet you were defeated by an office chair?"

"A spinny office chair!" Fred added, sticking an arm into the air. GoGo facepalmed, and Hiro couldn't help but laugh. No matter what happened, having his friends around him like this, bickering and joking around like always, would always make him feel better. Hiro hoped that, wherever Tadashi was now, he was with their parents and having just as good a time.

._._._._._._._._._._._._._._._.

Asset #2 was not having a good day.

Granted, he never really had a 'good' day, but at least he had some days where he wasn't treated as badly as normal and he actually had some time to himself. This would fall into one of those days where he just wondered why he was ever born in the first place. He had even reached the point of wishing he hadn't been born, if just so that he wouldn't have made such horrible things. He could deny his captors, of course; tell them that he wouldn't build their death machines, and that they would just have to find another robotics genius with memory problems. Then, of course, he would be tortured without remorse for hours on end until his voice had stopped working, his throat raw from screaming. And then he would be tortured even more. After all of that, he would agree to making whatever they had told him to make in the first place. He had decided, therefore, that it was pointless to openly rebel; it only brought him excruciating amounts of pain.

Today he hadn't denied them their machine; in fact, to them, this would have been a good, productive day. He had performed exactly as they wanted him to, not asking questions unless it was requesting certain materials for his project. But to Asset #2, he felt sick just looking at the monstrosity in front of him, sick at the thought that it had been his brainchild. It wasn't the first weapon of mass destruction his captors had forced him to make, and he doubted it was the last. But something about it just made it the worst of all, in his eyes. Maybe it was the fact that it was, fundamentally, so simple. There wasn't an abundance of fancy tech or materials involved in its making; while it could be created with those, he hadn't been allowed access until his design was met with approval. Despite being so simplistic in design, it was still fully capable of massacring hundreds of people at a time. It was about the size of a golf ball, and it didn't look very threatening; in fact, it looked just like a little round ball of metal, some sort of baseball knock off. But when it was activated, it would release an electric shock of 10,000 volts in a 1,000 meter radius. That was more than enough to fry anything it came into contact with. Of course, it was on a set time; the person who dropped it off had to be far enough away to where they wouldn't be toasted. But other than that it was nearly the perfect weapon. Small, easily concealable, and with a high success rate, at least in all of the tests that they had run. It was right up his captor's ally, and they had been extremely pleased with it. So much, in fact, that they allowed him alone time to tinker with a few nuts and bolts. Nothing that he could use to escape, but enough to give him the appearance of having leisure time.

He would have taken death a million times over than making that monstrosity.

But he couldn't change what he had done now. Anyway, he'd created many other horrible machines that were probably responsible for the deaths of hundreds of people by now. All of those people, dead because of him. It was enough to make him sick to his stomach, and wish desperately, once again, that he had never been born; all he was good for was ruining people's lives.

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Author's Note:

Hey everyone, sorry for such a long wait for the first official chapter. There's just been a lot of stuff going on with me. Also, sorry if this chapter doesn't flow very well; I'm still learning how to make that better. I can picture the whole thing in my head like a movie, but when I try to write it down it comes out awful. Of course. Anyway, thank you so much for reading! The next chapter should come out in about a week, or at least that's what I'll try to do. Like I said, things are pretty hectic for me right now and I don't know when I'll get time to write or even if I'll have the motivation to. Be safe, and I'll see you here next chapter!

Also, please note: I referred to Hiro as a young boy in the prologue. Please discount this! He is actually 17 years old. I feel like a big idiot for messing up like that, I'll try to edit it as soon as I can.

Ages for each character as follows:

Wasabi: 24

Honey Lemon: 24

Fred: 25

GoGo: 23

Hiro: 17

Asset #2 (I'm pretty sure you all know who he is, but I'll keep this up for now): 23

And everyone else is so on and so forth. Please let me know if you spot any discrepancies in my writing!


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